The field of the present invention relates to the delivery of energy impulses (and/or energy fields) to bodily tissues for therapeutic purposes. The invention relates more specifically to the use of electrical stimulation of the sphenopalatine ganglion (SPG) and other cranial nerves for treating disorders in a patient, such as primary headache.
The sphenopalatine ganglion (SPG) is a nerve ganglion found in the pterygopalatine (sphenopalatine) fossa, close to the sphenopalatine foramen (102 in FIG. 3; also known as the pterygopalatine ganglion, ganglion pterygopalatinum, Meckel's ganglion, and nasal ganglion). There are two SPG, on either side of the nose. The SPG is usually triangular or oblong, and in humans it is approximately 5 mm across its maximum extent. Its triangular shape reflects the three principal branches of the SPG: the vidian nerve superomedially, the branch from the maxillary nerve superolaterally, and the greater and lesser palatine nerves inferiorly. However, there is considerable SPG anatomical variation between individuals, and in some individuals, the SPG may not even exist as a single-unit structure [M. C. RUSU, F. Pop, G. C. Curca, L. Podoleanu, L. M. Voinea. The pterygopalatine ganglion in humans: A morphological study. Ann Anat 191 (2009):196-202].
The pterygopalatine fossa, within which the SPG is located, has the following boundaries: Anterior—the posterior wall of the maxillary sinus; Posterior—the medial plate of the pterygoid process; Medial—the perpendicular plate of the palatine bone; Superior—the sphenoid sinus; Lateral—communication with the infratemporal fossa; Superlateral—the maxillary branch of the trigeminal nerve exits the cranial vault through the foramen rotundum. The pterygopalatine fossa is approximately 1 cm wide and 2 cm high and can be viewed fluoroscopically as having the shape of a vase or pyramid on a lateral fluoroscopic view. Its neurovascular contents are complex, in which nerves and vessels of different individuals may occupy different locations within the fossa. Several surgical/anatomical routes have been described for reaching this fossa [Fabio ROBERT], Nicola Boari, Pietro Mortini, Anthony J. Caputy. The Pterygopalatine Fossa: An Anatomic Report. J Craniofac Surg 18(3,2007):586-590; Melissa McCarty STATHAM and Thomas A. Tami. Endoscopic anatomy of the pterygopalatine fossa. Operative Techniques in Otolaryngology—Head and Neck Surgery 17(3,2006):197-200; LI, Jiping; Xu, Xiongwei; Wang, Jiadong; Jing, Xiaojie; Guo, Qinhua; Qiu, Yongming. Endoscopic Study for the Pterygopalatine Fossa Anatomy: Via the Middle Nasal Meatus-Sphenopalatine Foramen Approach. Journal of Craniofacial Surgery 20(3,2009):944-947; Christoph P. HOFSTETTER, Ameet Singh, Vijay K. Anand, Ashutosh Kacker and Theodore H. Schwartz. The endoscopic, endonasal, transmaxillary transpterygoid approach to the pterygopalatine fossa, infratemporal fossa, petrous apex, and the Meckel cave. J Neurosurg 113 (2010):967-974; FORTES F S, Sennes L U, Carrau R L, Brito R, Ribas G C, Yasuda A, Rodrigues A J Jr, Snyderman C H, Kassam A B. Endoscopic anatomy of the pterygopalatine fossa and the transpterygoid approach: development of a surgical instruction model. Laryngoscope 118(1,2008):44-49; ALFIERI A, Jho H D, Schettino R, Tschabitscher M. Endoscopic endonasal approach to the pterygopalatine fossa: anatomic study. Neurosurgery 52(2,2003):374-380; CAVALLO LM, Messina A, Gardner P, Esposito F, Kassam A B, Cappabianca P, de Divitiis E, Tschabitscher M. Extended endoscopic endonasal approach to the pterygopalatine fossa: anatomical study and clinical considerations. Neurosurg Focus 19(1,2005):E5, pp. 1-7; ISAACS SJ, Goyal P. Endoscopic anatomy of the pterygopalatine fossa. Am J Rhinol 21(5,2007):644-647].
Although it is primarily considered to be a parasympathetic ganglion, the SPG also conveys both sensory and sympathetic fibers which—unlike parasympathetic fibers—only pass through the ganglion without synapsing. The SPG is innervated by the greater pertrosal nerve (a branch of the facial nerve, i.e., the seventh cranial nerve) and has other important connections with the trigeminal nerve (fifth cranial nerve, particularly the maxillary nerve CN V2), internal carotid artery plexus of the sympathetic nervous system and, at least in animals, the anterior pituitary gland. Thus, the SPG has a complex center (see FIG. 2). It joins the maxillary branch of the trigeminal nerve via the pterygopalatine nerves. It joins the vidian nerve (nerve of the pterygoid canal), which is formed from the greater petrosal and deep petrosal nerves. It also connects with the greater and lesser palatine nerves which give rise to superior, posterior, lateral nasal, and pharyngeal nerves [M. C. RUSU and F. Pop. The anatomy of the sympathetic pathway through the pterygopalatine fossa in humans. Annals of Anatomy 192 (2010):17-22].
The SPG has been a clinical target to treat severe headaches since SLUDER first described the application of cocaine or alcohol to the vicinity of the SPG, by swabbing through the nostril to the nasopharyngeal mucosa posterior to the middle turbinate. This local anesthetic readily penetrates the mucosa to diffuse to the SPG. Later, SLUDER described the following injection into the pterygopalatine fossa with a silver nitrate solution and phenol, in order to inactivate the SPG chemically. A needle bent at a right angle 0.5 cm from its end is introduced along the septum of the nose to a point 0.33 cm posterior to and slightly above the posterior tip of the middle turbinate. Turning the needle outward brings it to the membrane covering the sphenopalatine foramen, puncturing the membrane, thereby bringing the tip of the needle into the pterygopalatine fossa. Alternatively, a straight 12 cm needle (with 1.2 mm diameter) may be used to reach the fossa. The inactivating chemical solutions were then injected into the pterygopalatine fossa [Greenfield SLUDER. Etiology, diagnosis, prognosis, and treatment of sphenopaltine ganglion neuralgia. Transactions of the American Medical Association. Section on Laryngology, Otology and Rhinology, 1913 Chicago: A.M.A. Press pp. 43-64].
Unfortunately, the SPG swabbing produces only a brief respite from pain, whether by using a cotton swab as originally described by SLUTER, or by means of a topical administration device [U.S. Pat. No. 8,231,588, entitled Methods for ameliorating pain and devices for delivering a medicament, to XIA]. In addition, injection into the pterygopalatine fossa is difficult to perform reliably due to considerable anatomical variability of the patients, with damage to the maxillary artery that lies next to the SPG being not uncommon. Furthermore, the nasal mucosa may slough during needle insertion. Nevertheless, such pharmacological blockade of the SPG has been claimed to be an effective treatment for headaches, asthma, angina, hiccups, epilepsy, glaucoma, neck pain, vascular spasms, facial neuralgias, blindness, low back pain, sciatica, ear ache, menstrual pain, temporomandibular joint dysfunction, and hyperthyroidism [Robert E. WINDSOR and Scott Jahnke. Sphenopalatine Ganglion Blockade: A Review and Proposed Modification of the Transnasal Technique. Pain Physician 7 (2004):283-286].
More recently, anesthetic has been injected into the pterygopalatine fossa using modifications of the Sluder methods and devices [Athma PRASANNA and P. S. N. Murthy. Sphenopalatine ganglion block under vision using rigid nasal sinuscope. Regional Anesthesia 18 (1993): 139-140; Ian Y. YANG and Saeed Oraee. A Novel Approach to Transnasal Sphenopalatine Ganglion Injection. Pain Physician 9 (2006):131-134; FELISATI G, Arnone F, Lozza P, Leone M, Curone M, Bussone G. Sphenopalatine endoscopic ganglion block: a revision of a traditional technique for cluster headache. Laryngoscope 116(8,2006):1447-1450]. Nevertheless, the internal maxillary artery may be at risk no matter where the pterygopalatine fossa is punctured [ISAACS SJ, Goyal P. Endoscopic anatomy of the pterygopalatine fossa. Am J Rhinol 21(5,2007):644-647].
In addition to the ganglion blockade using anesthetics that is described above, ablation (percutaneous radiofrequency, gamma knife, and surgical gangionectomy) and electrical nerve stimulation have been used to treat pain (especially cluster headaches) originating in, or emanating from, the SPG. The objective of the ablation is to irreversibly damage the SPG to such an extent that it cannot generate the nerve signals that cause pain. This is not a preferred method because ablation would destroy useful neurophysiological functions of the SPG, notwithstanding the pain that the SPG may cause.
In contrast to ablation, the objective of electrical nerve stimulation is to reversibly damage or otherwise inhibit or block activity the SPG. A significant advantage of electrical stimulation over ablation is that it is a reversible procedure. In that regard, SPG neurostimulation resembles the stimulation of other nerves for the treatment of primary headache disorders [Brian JENKINS Stewart J. Tepper. Neurostimulation for Primary Headache Disorders, Part 1: Pathophysiology and Anatomy, History of Neuromodulation in Headache Treatment, and Review of Peripheral Neuromodulation in Primary Headaches. Headache 51 (2011):1254-1266; Brian JENKINS Stewart J. Tepper. Neurostimulation for Primary Headache Disorders: Part 2, Review of Central Neurostimulators for Primary Headache, Overall Therapeutic Efficacy, Safety, Cost, Patient Selection, and Future Research in Headache Neuromodulation. Headache 51 (2011):1408-1418].
There are several anatomical approaches to the SPG, comprising: 1) a transnasal route as described above; 2) a transoral approach with a dental needle up to the sphenopalatine foramen through the posterior palatine canal and; 3) a lateral approach with a straight needle to the pterygopalatine fossa through the infratemporal fossa; 4) an infrazygomatic approach, in which the skin entry is at a site overlying the pterygopalatine fossa, just inferior to the zygoma and anterior to the mandible. DuPLESSIS describes other routes through the mouth and outer skin of the face [M. DuPLESSIS, N. Naysa, M. C. Bosman. Preliminary results on a study to locate the pterygopalatine fossa using mathematical formulae. Clinical Anatomy 23(8,2010):931-935; Micah HILL, Rakesh K. Chandra, Robert C. Kern. Approaches to the pterygopalatine space—Caldwell-Luc and beyond. Operative Techniques in Otolaryngology 21 (2010):117-121; SYED M. I. and Shaikh A. Radiology of Non-Spinal Pain Procedures. A Guide for the Interventionist. Chapter 2. Head and Neck. pp. 5-42. Heidelberg: Springer, 2011].
Until the present invention, neither radiofrequency ablation nor electrical stimulation of the SPG has been disclosed using a transnasal route. Avoidance of the transnasal route has apparently been due to the fact that surgical access to the pterygopalatine fossa through the nose is considered difficult, because of the protected position of the fossa and because of its complex and somewhat variable neurovascular anatomy. Avoidance of a transnasal route has also been due to structural and energizing limitations of prior electrical stimulators, which would make their introduction through the nose essentially impossible.
Thus, all ablation and electrical stimulation methods to date have approached the SPG only via the transoral or infrazygomatic approaches. Investigators using ablation described use of the infrazygomatic approach [NAROUZE S, Kapural L, Casanova J, Mekhail N. Sphenopalatine ganglion radiofrequency ablation for the management of chronic cluster headache. Headache 49(4,2009):571-577; NAROUZE SN. Role of sphenopalatine ganglion neuroablation in the management of cluster headache. Curr Pain Headache Rep 14(2,2010):160-63].
When implanting an SPG electrical stimulator, IBARRA also used the infrazygomatic route, as did TEPPER and ANSARINIA. [IBARRA E. Neuromodulación del Ganglio Esfenopalatino para Aliviar los Síntomas de la Cefalea en Racimos. Reporte de un Caso. Boletín E I Dolor 46(16,2007): 12-18; Stewart J. TEPPER; Ali Rezai, Samer Narouze, Charles Steiner, Pouya Mohajer, Mehdi Ansarinia. Acute Treatment of Intractable Migraine With Sphenopalatine Ganglion Electrical Stimulation. Headache 49 (2009):983-989; Mehdi ANSARINIA, Ali Rezai, Stewart J. Tepper, Charles P. Steiner, Jenna Stump, Michael Stanton-Hicks, Andre Machado, Samer Narouze. Electrical Stimulation of Sphenopalatine Ganglion for Acute Treatment of Cluster Headaches. Headache 50 (2010):1164-1174; U.S. Pat. No. 6,526,318, entitled Stimulation method for the sphenopalatine ganglia, sphenopalatine nerve, or vidian nerve for treatment of medical conditions, to ANSARINIA].
On the other hand, SCHOENEN, PAPAY, and SHALEV used the transoral approach for electrical stimulation of the SPG [Jean SCHOENEN, Rigmor Højland Jensen, Michel Lanteri-Minet, Miguel J A Lainez, Charly Gaul, Amy M Goodman, Anthony Caparso and Arne May. Stimulation of the sphenopalatine ganglion (SPG) for cluster headache treatment. Pathway CH-1: A randomized, sham-controlled study. Cephalalgia. 2013 Jan. 11, pp. 1-15 [Epub ahead of print]; Application US20120209286, entitled Surgical guide and method for guiding a therapy delivery device into the pterygopalatine fossa, to PAPAY et al; Application US20110160623, entitled External stimulation of the SPG, to SHALEV; US20060195169, entitled Surgical tools and techniques for stimulation, to GROSS et al.; US20080172102, entitled Transmucosal electrical stimulation, to SHALEV].